One of the most commonly recognized difficulties associated with airplanes and other aircraft is fueling and defueling. Jet fuel, for example, is a flammable hydrocarbon liquid that can be ignited even in certain ambient conditions, primarily based on temperature and vapor concentration. The temperature at which the vapors of a flammable liquid can ignite is known as the “flash point.” A hazardous vapor concentration is present when a fuel vapor reaches a level known as the lower flammability limit (LFL) or lower explosive limit (LEL). These limits are usually expressed as a percentage by volume. Fuels below the LFL/LEL are considered too lean to burn. If the fuel vapor concentration exceeds the upper flammability limit or upper explosive limit, the fuel is considered too rich to burn. A fuel vapor concentration between these two limits is considered to be in its flammable range and will ignite and burn if exposed to an ignition source.
In addition, hydrocarbons, including jet fuel, may also present toxic or irritant hazards. Jet fuel and other hydrocarbons can affect the nervous system, causing headache, dizziness, and lack of coordination. Exposure to some hydrocarbons may also cause skin irritations if not controlled. Therefore, it is highly desirable to prevent or minimize human contact with fuel when fuelling or defueling an airplane.
Further, defueling an aircraft is a common occurrence. It is often desirable to defuel an aircraft before taking it out of service for maintenance or repair. Aircraft typically include one or more fuel drain valves to facilitate the defueling process. The drain valves can be attached to hoses to contain the draining fuel. Nevertheless, even after the majority of the fuel is drained through the drain valves, a significant amount of fuel often remains in the tank due to internal obstructions, low spots, and other phenomenon. Accordingly, sometimes tank access ports that may, for example, provide access to fuel pumps and other internal components, may be adjacent to pools of fuel even after defueling operations. In large aircraft, opening a tank access port following a defueling operation can still release tens to hundreds of gallons of fuel. Therefore, there is a need for an aircraft fuel containment system that minimizes the risk of contact with the fuel and fuel leaks as tank access ports are opened.